Arsenic sulfide as a potential anti-cancer drug

Arsenic sulfide (As(4)S(4)) is the main component of realgar, which is widely used in traditional Chinese medicine. Previous studies have shown the beneficial effects of As(4)S(4) in the treatment of hematological malignant diseases, however, its effects on solid tumors have yet to be fully elucidated. The current study aimed to explore the anti-cancer effect and the mechanism of As(4)S(4) on solid tumors in vitro and in vivo. Cells from four human solid tumor cell lines, including the MKN45 gastric cancer cell line, the A375 malignant melanoma cell line, the 8898 pancreatic carcinoma cell line and the HepG2 hepatocellular carcinoma cell line, were treated with As(4)S(4) in vitro, using the L02 embryonic liver cells as a control. The efficacy of As(4)S(4) was assessed in vivo using mice implanted with Lewis lung carcinoma cells. The results of the current study demonstrated that As(4)S(4) significantly inhibited the proliferation of solid tumor cells in a dose- and time-dependent manner, but produced a less pronounced effect on L02 cells. Additionally, As(4)S(4) was observed to induce apoptosis (including morphological changes and an enhanced sub-G(1) population), which was accompanied by the activation of caspase-3 and −9. Furthermore, treatment with As(4)S(4) significantly inhibited the growth of implanted tumors in mice. These results suggest that As(4)S(4) possesses potent in vitro and in vivo antitumor activity via the induction of cell apoptosis.